Menaquinone reduction by an HMT2-like sulfide dehydrogenase from Bacillus stearothermophilus
Bibliographic record
Abstract
The gene-encoding HMT2-like sulfide dehydrogenase from Bacillus stearothermophilus JCM2501 was amplified and expressed in Escherichia coli and the enzymatic features were examined. The enzyme was detected mainly in the membrane fraction. It catalyzed the sulfide-dependent menaquinone (MK) reduction showing special enzymatic features distinct from other sulfide-quinone oxidoreductases (SQRs) from autotrophic bacteria. The purified protein from E. coli brought about the sulfide-dependent 2,3-dimethyl-1,4-naphthoquinone (DMN) reduction in vitro. The reduction was accelerated in the presence of either cyanide or 2-mercaptoethanol and phospholipids. The high reduction was followed by a change in Km values for sulfide and DMN. The purified enzyme utilized MK as an electron acceptor in the membrane fraction from E. coli. Under anaerobic conditions, sulfide was oxidized with reduction of fumarate or nitrate via the MK pool. The dehydrogenase was different from SQR in autotrophic bacteria in terms of the low affinity for sulfide and the activity enhancement in the presence of cyanide or 2-mercaptoethanol. The sulfide oxidation via MK in the cellular membrane of Gram-positive bacteria was certified.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".